Mixtures comprising acrylonitrile polymers containing alkenyl carbonamides and polyacrylonitrile



United States Patent MIXTURES COMPRISING ACRYLGNl-TRILE POLY- ERSCONTAINING CARBONAM- IDES AND POLYACRYLUNITRILE Harry W. Cooyer, Jr.,and Joseph B. Dickey, Kingsport,

Tenn assigiors to Eastman Kodak flompany, Rochester, N. Y'., acorporation of New- Jersey N 0 Drawing. Application October 21, 1952',Serial No. 316,051

4- Claims. (Cl. 260-455) This invention relates to composite resinouscompositions comprising a mixture of acrylonitrile polymers-containingamide groups and polyaerylonitrile.

This application is, a continuation-in-part of our copending applicationSerial No. 198,761, filjed December l, 1950, now United StatesPatent2,620,324 which, discloses and claims the preparation of theacrylon-itrile polymers containing amide groups as employed inpracticing this invention and their utility as fiber-forming'materials.

it, is known that polyacryloni'trile fibers call be spun which haveexcellent physical properties such as high strength, high stickingtemperatures and good resistance to Shrinkage at elevated temperatures,However, such fibers show certain, disadvantageous properties whichseverely limit their commercial use such, as, low moisture absorptionand more. especially poor dyeability with most available dyes of thecellulose acetate, direct cotton, acid wool and vat types of dyes. For agreat many textile purposes, improved dyeability of polyacrylonitrile,fibers or fibers produced from polymers containing a high percentage ofacrylonitrile would be highly desirable.

It is further known that greatly increased moisture ab.- sorption anddyeability of acrylonitrile fibers can be obtained by copolymerizingacrylonitrile with certain other unsaturated compounds whosepolymers'are known to have good afiinity for various dyes. While thisprocedure does give polymeric products having improved dyeability, aserious drawback arises in certain instances in that the fiber producedshows, a materially lower softening point, thus limiting their practicaluses. Another procedure employed for the purpose of increasing the dyeaffinity of polyacrylonitrile has been to mix the, polyacrylonitrile,before spinning, with otherfilm-forming materials, which are known to bereadily dyeable. However, it has been well established thatacrylonitril'e polymers are incompatible with most, otherpolymericmaterials. Out of many hundreds of synthetic polymers that,have been tested, only a relatively small number of them have, been.found sulficiently compatible. For example, it can be demonstrated thatmixtures of polyacrylonitr-ile with polyvinyl acetate, when dissolved inN,N-dimethyl. formamide in proportions varying from 15 to. 50 percentby-weight of the polyvinyl acetate and from 85 to 50percent by weight ofthe polyacrylonitrile, form grainy, dopes which separate on standinginto two liquid layers, and, that fibers formed from such mixtures showsegmentation into their individual components along their horizontalaxes.

We have now found that stable, homogeneous solutions comprising twodilferent acrylonitrile polymers which do not separate into distinctlayers on standing, and from which fibers of good dyeability andexcellent physical properties can be spun, can be obtained by dissolvingin acrylonitrile polymer solvents, in individual order or in intimateadmixture polyacrylonitrile and an acrylonitrile polymer, the latterbeing=prepared by homopolymerizing acrylonitrile in the presence of anisolated polymer or interpolymer of an amide of an afimonoethylenicallyunsaturated aliphatic carboxylic acid eontainingsfrom-fi to 5 carbonatoms in the acid radical. The acrylonitri'le polymers andpolyacrylonitrile are compatible with one another in all proportions.

It is, accordingly, an object of our invention to provide composite,resinous compositions comprising certain acrylonitrile polymers,containing a,B-monoethylenically unsaturated aliphatic carboxylic amidegroups, intimately admixed with polyacrylonitrile. Another object is toprovide a process for preparing these compositions. A further object isto provide homogeneous and stable solutions of the compositions. A stillfurther object is to provide fibers prepared therefrom. Other objectswill become apparent from a considerationof the following descriptionand examples.

In accordance with our invention, we prepare the composite, resinouscompositions of the invention by intimately mixing or by dissolving inany proportions, but preferably in the proportion of from 5 to 95 partsby weight of an acrylonitrile polymer,';prepared by homopolymerizingfrom 5 to 95 percent by weight of acrylonitrile in the presence of from95 to 5 percent by weight of a polymer of an amide of anu,fi-monoethylenically unsaturated aliphatic carboxylic acid containingfrom 3 to 5 carbon atoms in the acid radical, and from 95 to 5 parts byweight of polyacrylonitrile in a solvent such as dimethyl formamide,dimethyl acetamide, gamma-butyrolactone, ethylene carbonate, ethylenecyanohydrin, etc.

The solutions thus obtained are clear and homogeneous and do notseparate into two layers on standing or during spinning operations.Fibers can be spun from such solutions (dopes) by eitherthe wet or dryspinning methods. The concentration of the polymers in the solvent canvary widely from very low (less than 1%) to much higher concentrations,butfor elficient operations the concentration is advantageously from5-20 percent or higher. The dopes are stable over the usual temperaturerange of operations for spinning.

The acrylonitrile polymers employed in the practice of our invention asone of the components of the mixture can be termed place polymers andare prepared by polymerizing acrylonitrile monomer in the presence ofcertain afl-monoethylenicall'y unsaturated aliphatic carbonamidehomopolymers or interpolymers. The homopolymers of the a,8-monoethylenically unsaturated aliphatic carbonamides areespecially-useful, although interpolymers there- 7 of can also be usedto advantage. Such interpolymers contain advantageously from 25 to 95percent by weight of the a,fi-monoethylenically unsaturated aliphaticcarbonamide and from to 5 percent by weight of another ethylenicallyunsaturated, polymerizable organic compound containinga -CH=C group ormore especially a CH2=C group, Formulas Band II, respectively. Suitableu,p-monoethylenically unsaturated aliphatic carbons amides whosepolymerscan advantageously be employed in practicing our inventioncomprise the acrylamides, citraconamides, itaconamides, maleamides, etc.(e. g'. amides of alkenyl carboxylic acids containing from 3 to 5 carbonatoms in theacid radical). The acrylamides provide polymers whichareespecially useful in practicing the invention. I V

The acrylamides whose polymers can be advantageously used in ourinvention comprise those represented by the following general formula:

0 R III. OH:==C.(. 7N

1 12 Rl wherein R and R each represents a hydrogen atom or alkyl group,siichas methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, etc.groups (e. g: an alkyl group of the formula CnH2n+I- wherein nrep'resentsa positive integer of: from 1 to 4), and 11 2 represents ahydrogen atom or a methyl group. Typical acrylamides include acrylamide,N-methylacrylamide, N-ethylacrylamide, N-isopropylacrylamide,N-n-butylacrylamide, methacrylamide, N- methylmethacrylamide,N-ethylmethacrylamide, N-isopropylmethacrylamide,N,N-dimethylacrylamide, N,N-diethylacrylamide,N,N-dimethylmethacrylarnide, etc.

The itaconamides whose polymers we can advantageously use comprise thoserepresented by the following general formula:

wherein R5, R6, R7, and Rs each represents a hydrogen atom, a methylgroup, an ethyl group, etc. Typical itaconamides include itaconamide,N-methyl itaconamide, N- ethyl itaconamide, N,N'-climethyl itaconamide,N,N-dimethyl itaconamide, etc.

The citraconamides whose polymers we can advantageously use comprisethose represented by the following general formula:

wherein R5, Rs, R7, and Rs have the values given above. Typicalcitraconamides include citraconamide, N-methyl citraconamide, N-ethylcitraconamide, N,N'-diethyl citraconamide, etc.

Other amides whose polymers are useful in practicing our inventioninclude, for example, e-chloroacrylamide, achloro-N-methylacrylamide,etc.

The monoethylenically unsaturated compounds represented by Formulas Iand Li, whose interpolymers are useful in practicing our invention,comprise the a,B-mn0- ethylenically unsatuated aliphatic carbonamidesrepresented by Formulas III, IV, and V above, as well as methylacrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butylacrylate, isobutyl acrylate, methyl methacrylate, ethyl methacrylate,n-propyl methacrylate, isopropyl rnethacrylate, n-butyl methacrylate,isobutyl methacrylate (e. g. alkyl acrylates containing from 1 to 4carbon atoms in the alkyl group), vinyl acetate, vinyl propionate,styrene, a-methylstyrene, p-acetaminostyrene, oc-acetoxystyrene, vinylchloride, vinylidene chloride, ethyl vinyl ether, isopropyl vinyl ether,isopropenyl methyl ketone, ethyl isopropenyl ketone, methyl vinylketone, ethyl vinyl ketone, dimethyl maleate, diethyl maleate,diisopropyl maleate, dimethyl fumarate, diethyl fumarate, diisopropylfumarate, acrylic acid, methacrylic acid, fumaronitrile, acrylonitrile,methacrylonitrile, N-vinylphthalimide, ethylene, vinyl fluoride,perfiuoroethylene, vinylpyridines, etc.

The polymerization is advantageously carried out in an aqueous medium,although other reaction media, such as organic solvents, can beemployed; for example, a polymerization medium consisting of aqueousacetone, or other aqueous solvent can be used.

The polymerization can be accelerated by the use of a well knownpolymerization catalyst. Such catalysts are commonly used in the art ofpolymerization, and our invention is not to be limited to any particularcatalyst material. Catalysts which have been found to be especiallyuseful comprise the peroxide polymerization catalysts, such as theorganic peroxides (e. g. benzoyl peroxide, acetyl peroxide, acetylbenzoyl peroxide, lauryl peroxide, oleoyl peroxide, triacetone peroxide,urea peroxide, tbutyl hydroperoxide, alkyl percarbonates, etc.),hydrogen peroxide, perborates (e. g. alkali metal perborates, such asthose of sodium and potassium, etc.), persulfates (e. g. alkali metalammonium persulfate, etc.). Other catalysts such as the ketazines,azines, etc. can be used. The

quantity of catalyst used can be varied, depending on the monomer,amount of diluent, etc.

The temperatures at which the process of our invention can be carriedout vary from ordinary room temperature to the reflux temperature of thereaction mixture. Generally a temperature of from 25 to C. issufficient.

If desired, emulsifying agents can be added to the reaction mixture todistribute uniformly the reactants throughout the reaction medium.Typical emulsifying agents include the alkali metal salts of certainalkyl acid sulfates (e. g. sodium lauryl sulfate), alkali metal salts ofaromatic sulfonic acids (sodium isobutylnaphthalenesulfonate), alkalimetal or amine addition salts of sulfosuccinic acid esters, alkali metalsalts of fatty acids containing from 12 to 20 carbon atoms, sulfonatedfatty acid amides, alkali metal salts of alkane sulfonic acids,sulfonated others, etc.

The polymerization can be carried out in the presence of chainregulators, such as hexyl, octyl, lauryl, dodecyl, myristyl mercaptans,etc., which impart improved solubility properties to the polymercompositions. If desired, reducing agents such as alkali metalbisulfites (e. g. potassium, sodium, etc. bisulfites) can be added toreduce the time required for the polymerization to be effected.

The polymer of the a,fl-monoethylenically unsaturated aliphaticcarbonamide can advantageously be suspended in an aqueous mediumcontaining the polymerization catalyst, and the suspension (or solution)heated for a time (e. g. 30 minutes to 24 hours) prior to the additionof the acrylonitrile, and the mixture then subjected to polymerizingconditions. Alternatively, the polymer of the a,B-monoethylenicallyunsaturated aliphatic carbonamide can be added to an aqueous mixture(solution or emulsion) containing the acrylonitrile and polymerizationcatalyst, and the mixture then subjected to polymerizing conditions. Theacrylonitrile monomer and the polymer of the a,;3-monoethylenicallyunsaturated aliphatic carbonamide can be mixed together, and the mixtureadded to an aqueous medium containing a polymerization catalyst.

The following examples will serve to illustrate further the mannerwhereby we practice our invention.

Example 1 2.0 g. of poly-N-methylacrylamide were dissolved in cc. ofwater containing 0.1 g. of ammonium persulfate, 0.1 g. of potassiumbisulfite, and 8.0 g. of acrylonitrile. The resulting solution wasallowed to polymerize for 16 hours at 25 C., and the resulting polymerwas filtered olf. After drying there was obtained a product weighing 8.7g. It was found to contain 19 percent by weight of N-methylacrylamide onanalysis.

The polymers can be mixed with polyacrylonitrile in all proportions anddissolved to give stable solutions which do not separate into distinctlayers on standing and from which fibers and films of homogeneouscharacter can be spun, extruded or cast.

Fibers obtained by preparing a solution of a mechanical mixture of onepart of the above polymer and one part or" polyacrylonitrile andextruding the solution into a precipitating bath, had a tenacity of 3.4g. per denier, an extensibility of 19 percent, a sticking temperature of2l0 C., and shrank only 8 percent in boiling water. The fibers contained9.5 percent N-methylacrylamide by analysis. I

Example 2 3.0 g. of an interpolymer of acrylonitrile andN-methylmethacrylamide containing 76 percent by weight of N-methylmethacrylamide were dissolved in 100 cc. of water, along with 0.1g. of ammonium persulfate and 0.1 g. of potassium bisulfite. Theresulting solution was tumbled end-over-end for 18 hours at 25 C., and7.0 g. of acrylonitrile were then added, and the polymerization allowedto continue for 48 hours at 25 C. The resulting polymeric material wasprecipitated by the addition of acetone, and then collected bycentrifuging. After drying, there were obtained 9.2 g. of polymericmaterial containing 19 percent by weight of N-methylmethacrylamide.

The polymers can be mixed with polyacrylonitrile in all proportions anddissolved to give stable solutions which do not separate into distinctlayers on standing and from which fibers and films of homogeneouscharacter can be spun, extruded or cast.

Fibers obtained from a solution of a mechanical mixture of 75 partspolyacrylonitrile and 25 parts of the above polymer and extruding thesolution into a precipitating bath, had a tenacity of 3.2 g. per denier,an extensibility of 21 percent, a sticking temperature of 205 C. andshrank only 6 percent in boiling water.

Example 3 1.0 g. of poly-N-isopropylacrylamide was added to 60 cc. ofwater containing 1 cc. of 7-ethyl-2-methylundecan- 4-sulfonic acidsodium salt (Tergitol No. 4). The mixture was then tumbled end-over-endfor 1 hour at 50 C. The solution was cooled and 8.5 g. of acrylonitrile,0.1 g. of ammonium persulfate, and 0.1 g. of sodium bisulfite wereadded. The polymerization was efiected by tumbling for 16 hours at 25C.. The polymer was obtained in an 85 percent yield and contained 10percent by weight of N-isopropylacrylamide.

The polymers can be mixed with polyacrylonitrile in all proportions anddissolved to give stable solutions which do not separate into distinctlayers on standing and from which fibers and fihns of homogeneouscharacter can be spun, extruded or cast.

Fibers obtained from a solution of a mechanical mixture of 5 partspolyacrylonitrile and 95 parts of the above polymer and extruding thesolution into a precipitating bath, had a tenacity of 3 grams perdenier, an extensibility of 23 percent, a sticking temperature of 220 C.and shrank only percent in boiling water.

Example 4 3.0 g. of an inter-polymer of N,N-dimethylacrylamide and vinylacetate containing 60 percent by weight of N,N- dimethylacrylamide weredissolved in 50 cc. of a 50 percent solution of acetonitrile in water.There were then added 6.0 g. of acrylonitrile, 0.1 g. of ammoniumpersulfate, and 0.1 g. of sodium bisulfite. The polymerization wasefiected by heating for 16 hours at 40 C. The precipitated polymer wasobtained in a 72 percent yield and contained 29 percent by weight of theamidevinyl acetate interpolymer upon analysis.

The polymers can be mixed with polyacrylonitrile in all proportions anddissolved to give stable solutions which do not separate into distinctlayers on standing and from which fibers and films of homogeneouscharacter can be spun, extruded or cast.

Fibers obtained from a solution of a mechanical mixture of 25 partspolyacrylonitrile and 75 parts of the above described polymer andextruding the solution into a precipitating bath, had a tenacity of 3.6g. per denier, an extensibility of 24 percent, a sticking temperature of200 C. and shrank only 8 percent in boiling water.

Example 5 2.0 g. of an interpolymer of N-methylacrylamide and acrylamidecontaining 30 percent by Weight of N-methylacrylamide were added to 70cc. of water containing 0.1 g. of sodium bisulfite and 9.0 g. ofacrylonitrile. The resulting solution was then polymerized for 16 hoursat 35 C. The polymer was filtered offand then dried. It was obtained inan 80 percent yield and was found to contain 17 percent by weight of theN-methylacrylamideacrylamide interpolymer on analysis.

The polymers can be mixed with polyacrylonitrile in all proportions anddissolved to give stable solutions which do not separate into distinctlayers on standing and from which fibers and films of homogeneouscharacter can be spun, extruded or cast.

Fibers obtained from a solution of a mechanical mixture of 10 partspolyacrylonitrile and 90 parts of the above polymer and extruding thesolution into a precipitating bath, had a tenacity of 3.1 g. per denier,an extensibility of 21 percent, a sticking temperature of 215 C. andshrank only 8 percent in boiling Water.

Example 6 4.0 g. of poly-N,N-dimethylmethacrylamide were dissolved incc. of acetonitrile containing 6.5 g. of acrylonitrile and 0.3 g. ofbenzoyl peroxide. The resulting solution was then heated for 24 hours at50 C., and then cooled. The precipitated polymer was collected on afilter, washed, and dried. It was found to contain 39 percent by weightof N,N-dimethylmethacrylamide on analysis.

The polymers can be mixed with polyacrylonitrile in all proportions anddissolved to give stable solutions which do not separate into distinctlayers on standing and from which fibers and films of homogeneouscharacter can be spun, extruded or cast.

Example 7 3.0 g. of an interpolyrner of citraconic diamide and methylmethacrylate containing 28 percent by weight of the diamide wereemulsified in 100 cc. of water containing 3 cc. of a sulfonated ethersuch as an aryloxy polyalkylene ether sulfonate (Triton 720). There wasthen added 7.0 g. of acrylonitrile, 0.15 g. of potassium persulfate, and0.1 g. of sodium bisulfite. The resulting emulsion was heated for 16hours at 35 C., and then cooled to room temperature. The precipitatedpolymer was collected on a filter, washed and dried. It contained 28percent by weight of the citraconic diamide-methyl methacrylateinterpolymer onanalysis.

The polymers can be mixed with polyacrylonitrile in. all proportions anddissolved to give stable solutions which do not separate into distinctlayers on standing and from which fibers and films of homogeneouscharacter can be spun, extruded or cast.

Example 8 9.5 g. of poly-N,N'-dimethylitaconic diamide were emulsifiedin 80 cc. of water containing 3 cc. of 7-methyl-2-methylundecan-4-sulfonic acid sodium salt (Tergitol No. 4). There wasthen added .5 g. of acrylonitrile, 0.05 g. of potassium persulfate, and0.05 g. of sodium bisulfite, and the emulsion was heated at 35 C. for 16hours with tumbling. The emulsion was then cooled to room temperature,the precipitated polymer filtered off, washed with distilled water, anddried. It was found to contain 5 percent acrylonitrile by analysis.

The polymers can be mixed with polyacrylonitrile in all proportions anddissolved to give stable solutions which do not separate into distinctlayers on standing and from which fibers and films of homogeneouscharacter can be spun, extruded or cast.

Fibers obtained from a solution of a mechanical mixture of parts ofpolyacrylonitrile and 10 parts of the above polymer and extruding thesolution into a precipitating bath, had a tenacity of 3.1 g. per denier,an extensibility of 20 percent, a sticking temperature of 210 C. andshank only 7 percent in boiling water.

Example 9 9 g. of an interpolymer of acrylamide and methyl acrylatecontaining 80 percent by weight of acrylamide were dissolved in cc. ofwater containing .05 g. of potassium persulfate, .05 g. of sodium.bisulfite, and 1 g. of acrylonitrile. The resulting solution was thenheated for 16 hours at 35 C. The solution was cooled to room temperatureand the precipitated polymer filtered oil, washed with distilled water,and finally dried.

The polymers can be mixed with polyacrylonitrile in all proportions anddissolved to give stable solutions which do not separate into distinctlayers on standing and from which fibers and films of homogeneouscharacter can be spun, extruded or cast.

A solution of a mechanical mixture of 50 parts polyacrylonitrile and 50parts of the above polymer was cast to give a clear, tough film.

Example 10 8 g. of poly-N-methylmethacrylamide were dissolved in 100 cc.of Water to which g. of ammonium persulfate and $1 g. of sodiumbisulfite, and 2 g. of acrylonitrile were added. The resulting solutionwas heated for 16 hours at 30 C., then cooled to room temperature. Theprecipitated polymer was filtered off, washed with distilled water, andthen dried.

The polymers can be mixed with polyacrylonitrile in all proportions anddissolved to give stable solutions which do not separate into distinctlayers on standing and from which fibers and films of homogeneouscharacter can be spun, extruded or cast.

Example 11 6 g. of an interpolymer of N-methylmethacrylamide andacrylonitrile containing 70 percent by weight of N- methylmethacrylamidewere dissolved in 100 cc. of water containing 0.1 g. of potassiumpersulfate, 0.1 g. of sodium bisulfite, and 4 g. of acrylonitrile. Theresulting solution was then heated for 12 hours at 35 C. The solutionwas cooled to room temperature, and the precipitated polymer filteredoff, washed, and dried.

The polymers can be mixed with polyacrylonitrile in all proportions anddissolved to give stable solutions which do not separate into distinctlayers on standing and from which fibers and films of homogeneouscharacter can be spun, extruded or cast.

Fibers obtained from a solution of mechanical mixture containing 50parts polyacrylonitrile and 50 parts of the above polymer and extrudingthe solution into a precipitating bath had a tenacity of 3.2 g. perdenier, an extensibility of 23 percent, a sticking temperature of 210C., and shrank only 8 percent in boiling Water.

The mixtures of the invention which have a combined acrylonitrilecontent by weight of from 60 to 95 percent, the remainder of thecomposite composition being made up of other of the mentioned componentsof the invention, are particularly useful. for preparing fiber-formingmaterials. However, the above compositions, together with the compositecompositions which have a combined acrylonitrile content by weight offrom to 60 percent, the remainder of the composite composition in eachcase being made up of other of the mentioned components of theinvention, can all be made up into solutions or dopes in the mentionedsolvents, with or without fillers, pigments. dyes, plasticizers, etc.,as desired, and the dopes coated on a smooth surface to give flexibleand tough films and sheet materials, which are useful for photographicfilm support and other purposes.

Other solvents which can be used for the preparation of fibers andcoating compositions from the new polymer mixtures of our inventioninclude ethylene carbamate, N-methyl-2-pyrrolidone,N,N-dimethylmethoxyacetamide, dimethyl cyanamide, N,N-dimethylcycanoacetamide, N,N-dimethyl-fl-cyanopropionamide, glycolonitrile(formaldehyde cyanohydrin), malononitrile, dimethylsulfoxide, dimethylsulfone, tetramethylene sulfone, tetramethylene sulfoxide,N-formylpyrrolidine, N-formylmorpholine, N,N-tetramethylenemethanephosphonamide, and the like.

In addition to the above-described mixtures, we have found that theacrylonitrile polymers containing alkenyl carbonamides can also be mixedwith each other or with other acrylonitrile polymers containing at leastpercent by weight of acrylonitrile and 15 percent by weight of anothermonoethylenically unsaturated, polymerizable compound containing a CH=group .or a CH2= group, to give generally similar stable homogeneoussolutions.

What we claim is:

1. A mixture consisting of (1) from 5 to parts by weight of a graftcopolymer consisting of from 5 to 95% by weight of acrylonitrile andfrom 95 to 5% by weight of a preformed isolated polymer selected fromthe group consisting of a homopolymer of an unsaturated amide compoundrepresented by the following general formula:

wherein R represents an alkyl group containing from 1 to 4 carbon atomsand R2 represents a member selected from the group consisting of ahydrogen atom and a methyl group, and an interpolymer consisting of from25 to 95 by weight of the said unsaturated amide compound and 75 to 5%by weight of acrylonitrile and (2) from 95 to 5 parts by weight ofpolyacrylonitrile, the total weight of acrylonitrile in the said mixturebeing at least 60% and the weight of the said preformed isolated polymerin the said mixture being at least 5%.

2. A mixture consisting of (1) from 5 to 95 parts by weight of a graftcopolymer consisting of from 5 to 95% by weight of acrylonitrile andfrom 95 to 5% by weight of preformed isolated poly-N-methylmethacrylamide and (2) from 95 to 5 parts by weight ofpolyacrylonitrile, the total weight of acrylonitrile in the said mixturebeing'at least 60% and the weight of the said preformed isolatedpoly-N-methyl methacrylamide in the said mixture being at least 5%.

3. A mixture consisting of (1) from 5 to 95 parts by weight of a graftcopolymer consisting of from 5 to 95 by weight of acrylonitrile and from95 to 5% by weight of preformed isolated poly-N-isopropylacryla1nide and(2) from 95 to 5 parts by weight of polyacrylonitrile, the total weightof acrylonitrile in the said mixture being at least 60% and the weightof the said preformed isolated poly-N-isopropylacrylamide in the saidmixture being at least 5%.

4. A mixture consisting of (1) from 5 to 95 parts by weight of a graftcopolymer consisting of from 5 to 95 by weight of acrylonitrile and from95 to 5% by weight of a preformed isolated interpolymer consisting offrom 25 to 95 by weight of N-methyl methacrylamide and from 75 to 5% byweight of acrylonitrile and (2) from 95 to 5 parts by weight ofpolyacrylonitrile, the total weight of acrylonitrile in the said mixturebeing at least 60% and the weight of the said preformed isolatedinterpolymer in the said mixture being at least 5 References Cited inthe file of this patent UNITED STATES PATENTS 2,067,234 Gordon et al.Jan. 12, 1937 2,133,257 Strain Oct. 11, 1938 2,311,548 Jacobson et al.Feb. 16, 1943 2,425,192 Kropa Aug. 5, 1947 2,589,055 Coover et al Mar.11, 1952 2,620,324 Coover et al. Dec. 2, 1952 2,649,434 Coover et al.Aug. 18, 1953 2,688,008 Chaney et a1 Aug. 31, 1954

1. A MIXTURE CONSISTING OF (1) FROM 5 TO 95 PARTS BY WEIGHT OF A GRAFT COPOLYMER CONSISTING OF FROM 5 TO 95% BY WEIGHT OF ACRYLONITRILE AND FROM 95 TO 5% BY WEIGHT OF A PERFORMED ISOLATED POLYMER SELECTED FROM THE GROUP CONSISTING OF A HOMOPOLYMER OF AN UNSATURATED AMIDE COMPOUND REPRESENTED BY THE FOLLOWING GENERAL FORMULA: 